Fabio Oscari

Effect of task-related continuous auditory feedback during learning of tracking motion exercises.

BackgroundThis paper presents the results of a set of experiments in which we used continuous auditory feedback to augment motor training exercises. This feedback modality is mostly underexploited in current robotic rehabilitation systems, which usually implement only very basic auditory interfaces. Our hypothesis is that properly designed continuous auditory feedback could be used to represent temporal and spatial information that could in turn, improve performance and motor learning.MethodsWe implemented three different experiments on healthy subjects, who were asked to track a target on a screen by moving an input device (controller) with their hand. Different visual and auditory feedback modalities were envisaged. The first experiment investigated whether continuous task-related auditory feedback can help improve performance to a greater extent than error-related audio feedback, or visual feedback alone. In the second experiment we used sensory substitution to compare different types of auditory feedback with equivalent visual feedback, in order to find out whether mapping the same information on a different sensory channel (the visual channel) yielded comparable effects with those gained in the first experiment. The final experiment applied a continuously changing visuomotor transformation between the controller and the screen and mapped kinematic information, computed in either coordinate system (controller or video), to the audio channel, in order to investigate which information was more relevant to the user.ResultsTask-related audio feedback significantly improved performance with respect to visual feedback alone, whilst error-related feedback did not. Secondly, performance in audio tasks was significantly better with respect to the equivalent sensory-substituted visual tasks. Finally, with respect to visual feedback alone, video-task-related sound feedback decreased the tracking error during the learning of a novel visuomotor perturbation, whereas controller-task-related sound feedback did not. This result was particularly interesting, as the subjects relied more on auditory augmentation of the visualized target motion (which was altered with respect to arm motion by the visuomotor perturbation), rather than on sound feedback provided in the controller space, i.e., information directly related to the effective target motion of their arm.ConclusionsOur results indicate that auditory augmentation of visual feedback can be beneficial during the execution of upper limb movement exercises. In particular, we found that continuous task-related information provided through sound, in addition to visual feedback can improve not only performance but also the learning of a novel visuomotor perturbation. However, error-related information provided through sound did not improve performance and negatively affected learning in the presence of the visuomotor perturbation.

Substituting auditory for visual feedback to adapt to altered dynamic and kinematic environments during reaching

The arm movement control system often relies on visual feedback to drive motor adaptation and to help specify desired trajectories. Here we studied whether kinematic errors that were indicated with auditory feedback could be used to control reaching in a way comparable with when vision was available. We randomized twenty healthy adult subjects to receive either visual or auditory feedback of their movement trajectory error with respect to a line as they performed timed reaching movements while holding a robotic joystick. We delivered auditory feedback using spatialized pink noise, the loudness and location of which reflected kinematic error. After a baseline period, we unexpectedly perturbed the reaching trajectories using a perpendicular viscous force field applied by the joystick. Subjects adapted to the force field as well with auditory feedback as they did with visual feedback and exhibited comparable after effects when the force field was removed. When we changed the reference trajectory to be a trapezoid instead of a line, subjects shifted their trajectories by about the same amount with either auditory or visual feedback of error. These results indicate that arm motor networks can readily incorporate auditory feedback to alter internal models and desired trajectories, a finding with implications for the organization of the arm motor control adaptation system as well as sensory substitution and motor training technologies.

Improving robotics for neurorehabilitation: Enhancing engagement, performance, and learning with auditory feedback

This paper reports on an ongoing research collaboration between the University of Padua and the University of California Irvine, on the use of continuous auditory-feedback in robot-assisted neurorehabilitation of post-stroke patients. This feedback modality is mostly underexploited in current robotic rehabilitation systems, that usually implement very basic auditory feedback interfaces. The results of this research show that generating a proper sound cue during robot assisted movement training can help patients in improving engagement, performance and learning in the exercise.

Effects of Kinesthetic and Cutaneous Stimulation During the Learning of a Viscous Force Field

Haptic stimulation can help humans learn perceptual motor skills, but the precise way in which it influences the learning process has not yet been clarified. This study investigates the role of the kinesthetic and cutaneous components of haptic feedback during the learning of a viscous curl field, taking also into account the influence of visual feedback. We present the results of an experiment in which 17 subjects were asked to make reaching movements while grasping a joystick and wearing a pair of cutaneous devices. Each device was able to provide cutaneous contact forces through a moving platform. The subjects received visual feedback about joysticks position. During the experiment, the system delivered a perturbation through (1) full haptic stimulation, (2) kinesthetic stimulation alone, (3) cutaneous stimulation alone, (4) altered visual feedback, or (5) altered visual feedback plus cutaneous stimulation. Conditions 1, 2, and 3 were also tested with the cancellation of the visual feedback of position error. Results indicate that kinesthetic stimuli played a primary role during motor adaptation to the viscous field, which is a fundamental premise to motor learning and rehabilitation. On the other hand, cutaneous stimulation alone appeared not to bring significant direct or adaptation effects, although it helped in reducing direct effects when used in addition to kinesthetic stimulation. The experimental conditions with visual cancellation of position error showed slower adaptation rates, indicating that visual feedback actively contributes to the formation of internal models. However, modest learning effects were detected when the visual information was used to render the viscous field.

Development of a haptic teleoperation system for remote motor and functional evaluation of hand in patients with neurological impairments

The use of haptic devices in rehabilitation is becoming rather popular, given the proven effectiveness of such devices in stimulating the proprioceptive and tactile sensing of the users. In a standard framework, such devices are used in a local scenario, where the patient interacts with virtual manipulation experiments, presented on a computer screen. In this paper, we propose an extension of this standard approach by allowing the therapist to remotely interact with the patient, in order to remotely assess the degree of progress (or recovery) and, in turn, properly design new rehabilitation exercises. We apply the proposed concept on single d.o.f., bilateral system, based on two hand orthosis, one used as a master device by the therapist and the other applied to the patients hand. By using the master device (which incorporates a hand prosthesis, to make the manipulation more realistic), the therapist can remotely move the patients hand and, at the same time, thanks to the bilateral force feedback, he/she can perceive the patients resistance to the motion, allowing the remote motor and functional evaluation of the hand.

First Test Results of a Haptic Tele-Operation System to Enhance Stability of Telescopic Handlers

According to a recent report of ILO (International Labour Organization), more than two million people die or loose the working capability every year because of accidents or work-related diseases. A large portion of these accidents are related to the execution of motion and transportation tasks involving heavy duty machines. The insufficient degree of interaction between the human operator and the machine may be regarded as one of the major causes of this phenomenon. The main goal of the tele-operation system presented in this paper is to both preserving slave (machine) stability, by reducing the inputs of slave actuators when certain unsafe working conditions occur, and improving the level of interaction at master (operator) side. Different control schemes are proposed in the paper, including several combinations of master and slave control strategies. The effectiveness of the algorithms is analyzed by presenting some experimental results, based on the use of a two degrees-of-freedom force feedback input device (with one active actuator and one passive stiff joint) coupled with a simulator of a telescopic handler.© 2010 ASME

Changes in muscle coordination patterns induced by exposure to a viscous force field

BackgroundRobotic neurorehabilitation aims at promoting the recovery of lost function after neurological injury by leveraging strategies of motor learning. One important aspect of the rehabilitation process is the improvement of muscle coordination patterns, which can be drastically altered after stroke. However, it is not fully understood if and how robotic therapy can address these deficits. The aim of our study was to find how muscle coordination, analyzed from the perspective of motor modules, could change during motor adaptation to a dynamic environment generated by a haptic interface.MethodsIn our experiment we employed the traditional paradigm of exposure to a viscous force field to subjects that grasped the handle of an actuated joystick during a reaching movement (participants moved directly forward and back by 30 cm). EMG signals of ten muscles of the tested arm were recorded. We extracted motor modules from the pooled EMG data of all subjects and analyzed the muscle coordination patterns.ResultsWe found that the participants reacted by using a coordination strategy that could be explained by a change in the activation of motor modules used during free motion and by two complementary modules. These complementary modules aggregated changes in muscle coordination, and evolved throughout the experiment eventually maintaining a comparable structure until the late phase of re-adaptation.ConclusionsThis result suggests that motor adaptation induced by the interaction with a robotic device can lead to changes in the muscle coordination patterns of the subject.

Design and Construction of a Bilateral Haptic System for the Remote Assessment of the Stiffness and Range of Motion of the Hand

The use of haptic devices in the rehabilitation of impaired limbs has become rather popular, given the proven effectiveness in promoting recovery. In a standard framework, such devices are used in rehabilitation centers, where patients interact with virtual tasks, presented on a screen. To track their sessions, kinematic/dynamic parameters or performance scores are recorded. However, as Internet access is now available at almost every home and in order to reduce the hospitalization time of the patient, the idea of doing rehabilitation at home is gaining wide consent. Medical care programs can be synchronized with the home rehabilitation device; patient data can be sent to the central server that could redirect to the therapist laptop (tele-healthcare). The controversial issue is that the recorded data do not actually represent the clinical conditions of the patients according to the medical assessment scales, forcing them to frequently undergo clinical tests at the hospital. To respond to this demand, we propose the use of a bilateral master/slave haptic system that could allow the clinician, who interacts with the master, to assess remotely and in real time the clinical conditions of the patient that uses the home rehabilitation device as the slave. In this paper, we describe a proof of concept to highlight the main issues of such an application, limited to one degree of freedom, and to the measure of the stiffness and range of motion of the hand.

Functional Design of a Robotic Gripper for Adaptive Robotic Assembly

Nowadays, automated production systems are rapidly changing to increase flexibility. However, robot end effectors are usually designed to accomplish specific tasks and to handle a limited family of parts, and flexibility can only be obtained by using tool changing systems. The main drawbacks of such systems are increased cost of automation and reduced productivity. This paper presents the functional design of a flexible robotic gripper, capable of adaptively changing its aperture (grasp width) to different handling demands, without affecting the cycle time of the production system, as it can be actuated in hidden time. The solution proposed consists of (1) an electrically-actuated mechanism for adapting aperture, which allows to satisfy the flexibility requirements; (2) a pneumatically-actuated mechanism for open/close operations, which ensures comparably fast motion of jaws if compared to traditional, non-adaptive robotic grippers.

Agility in assembly systems: a comparison model

Purpose This paper aims at analyzing different possible assembly systems, including innovative potential configurations such as the fully flexible assembly systems (FAS), by defining a novel analytical model that focuses on the concept of agility and its impact on the whole system performance, also evaluating the economic convenience in terms of the unit direct production cost. Design/methodology/approach The authors propose a comparison model derived by Newton’s second law, introducing a quantitative definition of agility (acceleration), resistance of an assembly system to any change of its operative state (inertia) and unit direct production cost (force). Different types of assembly systems (manual, flexible and fully FAS) are analyzed and compared using the proposed model, investigating agility, system inertia and their impact on the unit direct production cost. Findings The proposed agility definition and the proposed comparison model have been applied considering different sets of parameters as independent variables, such as the number of components to assemble (product model complexity) and the target throughput of the system. The main findings are a series of convenience areas which either, for a given target unit direct production cost (force), defines the most agile system to adopt or, for a given target agility (acceleration), defines the most economical system to adopt, as function of the independent variables. Originality/value The novelty of this work is, first, the analytical definition of agility applied to assembly systems and contextualized by means of the definition of the new comparison model. The comparison between different assembly systems on the basis of agility, and by using different sets of independent variables, is a further element of interest. Finally, the resulting convenience areas represent a desirable tool that could be used to optimally choose the most suitable assembly system according to one or more system parameters.